As long as companies, and consumers, still pick Windows and Office, then why spend the resources. Making Windows better won't move the sales number significantly, but removing the ads and the potential AI upsell is a direct hit to revenue.
The sad reality seems to be that Microsoft do not care about the majority of their products anymore. Only Azure, Microsoft 365 CoPilot, CoPilot and maybe CoPilot.
I'm not familiar with many "consumers" who still pick a Windows and Office, and in this generation, there are very few consumers picking xbox. Outside of enterprises, they seem to be losing market share everywhere, and at this rate they'll be akin to IBM or Oracle in a few years.